Synchrotron micro tomographic evaluation of multilayered zirconia ceramics —Volumetric effects after indentation

• Multilayered composites of cubic and tetragonal stabilized zirconia were produced by electrophoretic deposition.
• Volumetric changes after indentation were analyzed using synchrotron-based X-ray μCT measurements in conjunction with surface sensitive methods like AFM, Raman spectroscopy and white light interferometry.
• In this work we were able to discriminate between the high and low content yttria layers due to differences in X-ray absorption.
• In this work we were able to relate volume changes to the transformation toughening effect after indentation in three dimensions.

Electrophoretic deposition was used to produce zirconia specimen consisting of alternating layers of fully stabilized cubic zirconia and partially stabilized tetragonal zirconia. In this configuration, the tetragonal stabilized zirconia layers can undergo transformation toughening upon mechanical induced stresses, while the cubic stabilized layers can act as confining element.To understand the volumetric changes due to transformation toughening in these layered materials after indentation, we used an advanced synchrotron-based X-ray μCT setup and compared the results with surface sensitive methods like Raman spectroscopy, AFM and white light interferometry.The high spatial resolution and the adapted beam energy between the absorption edges of zirconia and yttria allowed discriminating between individual layers due to differences in their yttria content. Furthermore we were able to identify single indents and link volume changes to different physical effects in the different stabilized zirconia parts and visualize the three dimensional volume around only few micrometre sized indents.